How to understand Domain Name System By Clare Lawrence 13th August 2004
Ever wonder why DNS systems came into existence? Efficiency. Every computer has a distinct IP address, and Internet needed an elite method for obtaining these addresses and for managing system as a whole. Enter ICANN.
The Internet Corporation for Assigned Names and Number manages DNS root of Internet domain namespace. ICANNís role is to manage assignment of identifiers, ensuring that all users have unique names.
The DNS system is run by a series of servers called DNS servers. ICANN manages root DNS domains, under which are top-level domains. It also manages:
Organizational domains Geographical domains Reverse domains
Beneath top-level domains are other naming authorities such as Nominet, UKís naming authority.
How does a DNS Query work?
The process occurs in two parts. Firstly, a name query begins at a client computer and is passed to DNS client service for resolution. When query cannot be resolved locally, DNS servers are queried.
For example, when a web browser calls fully qualified domain name www.discountdomainsuk.com, request is passed on to DNS client service to resolve name by using locally cached information. If query is held in cache, then process is complete.
If, however, query cannot be answered locally, DNS client service uses a server list (ordered in sequence) to query external DNS servers. When a DNS server receives a query, it first checks to see if it is authoritive for that domain name. If it is authoritive, it resolves name, and process is complete.